Over the last four hundred or so years, human beings have achieved something truly amazing: we understand the basic rules governing the operation of the world around us. Everything we see in our everyday lives is simply a combination of three particles - protons, neutrons, and electrons - interacting through three forces - gravity, electromagnetism, and the strong nuclear force. That is it; there are no other forms of matter needed to describe what we see, and no other forces that affect how they interact in any noticeable way. And we know what those interactions are, and how they work. Of course there are plenty of things we don't know - there are additional elementary particles, dark matter and dark energy, mysteries of quantum gravity, and so on. But none of those is relevant to our everyday lives (unless you happen to be a professional physicist). As far as our immediate world is concerned, we know what the rules are. A staggeringly impressive accomplishment, that somehow remains uncommunicated to the overwhelming majority of educated human beings.

That doesn't mean that all the interesting questions have been answered; quite the opposite. Knowing the particles and forces that make up our world is completely useless when it comes to curing cancer, buying a new car, or writing a sonnet. (Unless your sonnet is about the laws of physics.) But there's no question that this knowledge has crucial implications for how we think about our lives. Astrology does not work; there is no such thing as telekinesis; quantum mechanics does not tell you that you can change reality just by thinking about it. There is no life after death; there's no spiritual essence that can preserve a human consciousness outside its physical body. Life is a chemical reaction; there is no moment at conception or otherwise when a soul is implanted in a body. We evolved as a result of natural processes over the history of the Earth; there is no supernatural intelligence that created us and maintains an interest in our behavior. There is no Natural Law that specifies how human beings should live, including who they should marry. There is no strong conception of free will, in the sense that we are laws unto ourselves over and above the laws of nature. The world follows rules, and we are part of the world.